Microbiology, 2021

E • Glossary 1179
destruction by specific antibodies and
then killed by secretion of cytotoxins by
natural killer cells, macrophages, or
eosinophils
anticodon three-nucleotide sequence of a
mature tRNA that interacts with an mRNA
codon through complementary base
pairing
antigen (also, immunogen) a molecule
that stimulates an adaptive immune
response
antigenic able to stimulate an adaptive
immune response
antigenic drift form of slight antigenic
variation that occurs because of point
mutations in the genes that encode
surface proteins
antigenic shift form of major antigenic
variation that occurs because of gene
reassortment
antigenic variation changing of surface
antigens (carbohydrates or proteins) such
that they are no longer recognized by the
host’s immune system
antigen-presenting cells (APC)
macrophages, dendritic cells, and B cells
that process and present foreign pathogen
antigens for the purpose of activating T
cells and adaptive immune defenses
antimetabolites compounds that are
competitive inhibitors for bacterial
metabolic enzymes
antimicrobial drugs chemical
compounds, including naturally produced
drugs, semisynthetic derivatives, and
synthetic compounds, that target specific
microbial structures and enzymes, killing
specific microbes or inhibiting their
growth
antimicrobial peptides (AMPs) class of
nonspecific, cell-derived chemical
mediators with broad-spectrum
antimicrobial properties
antiparallel two strands of DNA helix
oriented in opposite directions; one strand
is oriented in the 5’ to 3’ direction, while
the other is oriented in the 3’ to 5’
direction
antisense RNA small noncoding RNA
molecules that inhibit gene expression by
binding to mRNA transcripts via
complementary base pairing
antisense strand transcription template
strand of DNA; the strand that is
transcribed for gene expression
antisepsis protocol that removes potential
pathogens from living tissue
antiseptic antimicrobial chemical that can
be used safely on living tissue
antiserum serum obtained from an
animal containing antibodies against a
particular antigen that was artificially
introduced to the animal
apoenzyme enzyme without its cofactor or
coenzyme
apoptosis programmed and organized cell
death without lysis of the cell
arachnoid mater middle membrane
surrounding the brain that produces
cerebrospinal fluid
arboviral encephalitis infection by an
arthropod-borne virus that results in an
inflammation of the brain
arbovirus any of a variety of viruses that
are transmitted by arthropod vectors
archaea any of various unicellular
prokaryotic microorganisms, typically
having cell walls containing
pseudopeptidoglycan
Archaea domain of life separate from the
domains Bacteria and Eukarya
artemisinin antiprotozoan and antifungal
drug effective against malaria that is
thought to increase intracellular levels of
reactive oxygen species in target microbes
artery large, thick-walled vessel that
carries blood from the heart to the body
tissues
Arthus reaction localized type III
hypersensitivity
artificial active immunity immunity
acquired through exposure to pathogens
and pathogen antigens through a method
other than natural infection
artificial passive immunity transfer of
antibodies produced by a donor to another
individual for the purpose of preventing or
treating disease
ascariasis soil-transmitted intestinal
infection caused by the large nematode
roundworm Ascaris lumbricoides
ascocarps cup-shaped fruiting bodies of
an ascomycete fungus
ascospore asexual spore produced by
ascomycete fungi
ascus structure of ascomycete fungi
containing spores
asepsis sterile state resulting from proper
use of microbial control protocols
aseptic technique method or protocol
designed to prevent microbial
contamination of sterile objects, locations,
or tissues
aspergillosis fungal infection caused by
the mold Aspergillus;
immunocompromised patients are
primarily at risk
asymptomatic carrier an infected
individual who exhibits no signs or
symptoms of disease yet is capable of
transmitting the pathogen to others
asymptomatic not exhibiting any
symptoms of disease
atomic force microscope a scanning
probe microscope that uses a thin probe
that is passed just above the specimen to
measure forces between the atoms and the
probe
ATP synthase integral membrane protein
that harnesses the energy of the proton
motive force by allowing hydrogen ions to
diffuse down their electrochemical
gradient, causing components of this
protein to spin, making ATP from ADP and
P i
attachment binding of phage or virus to
host cell receptors
attenuation regulatory system of
prokaryotes whereby secondary stem-loop
structures formed within the 5’ end of an
mRNA being transcribed determine both if
transcription to complete the synthesis of
this mRNA will occur and if this mRNA will
be used for translation
autoclave specialized device for the moistheat
sterilization of materials through the
application of pressure to steam, allowing
the steam to reach temperatures above the
boiling point of water
autocrine function refers to a cytokine
signal released from a cell to a receptor on
its own surface
autograft tissue transplanted from a
location on an individual to a different
location on the same individual
autoimmune disease loss of tolerance to
self, resulting in immune-mediated
destruction of self cells and tissues
autoinducer signaling molecule produced